Switch device for electric drills



Sept. 29, 1936. F` B HAMERLY 2,055,863

SWITCH DEVICE FORl ELECTRIC DRILLS Filed OCT.. 18, 1955 n n n INVENTOR.v /f//v/f /f/i/WZ BY m, W A

7% 7W l W.

ATTORNEYS Patented Sept. 29,1936 f PATENT dOFFICE n aosslaes swrrcnfnavrce Fon. ELECTRIC nmLLs' Frank B. Hamerly, Aurora, lill., assignor to Independent Pneumaticjool Co., Chicago, Ill., a

, corporation o! Delaware Application October 18, 1935, Serial No. 45,544

6 Claims.

This invention relates to relatively small portable electric hand drills of the gun or pistol type. 'The drill is held in and supported by one hand grasping the body of the drill on opposite sides and the single handle at the rear end of the drill.

'I'he handle is of the pistol grip type and is preferably made hollow to provide an air duct for the cooling system for the motor and to accommodate one of the brushes of the Amotor and the connector by which said brush is electrically connected to, one of the electric supply wires for the drill.

Themotor is of the horseshoe type thereby disposing the field coil of the motor above its armatureA and thus providing space in the drill casing above the. armature to accommodate the other brush and the switch device which is operable by the thumb of the hand grasping 4the drill to start and stop the motor. l 2o The general purpose and object of my invention is to provide an improved switch device having its insulating casing composed of a pair of separable overlapping sections and secured together in assembled relation by a single fastening element to simplify 'the switch construction and reduce its cost of manufacture. s'

A further object of my invention is`to provide the switch casing sections with intertting parts, preferably about the fastening element, to hold the sections against displacement in the plane of their meeting edges.

A further object of my invention is to make Fig. 1 is a side view of a small portable electric hand drill provided with a switch device of my invention, the outer casing ofthe drill land as- `sociated member of the handle being broken away and. in section, respectively, to show the switch device;

Fig. 2 is a horizontal sectional view taken through the drill at the switch device on line 2-2 of Fis. 1; 1Fi`g. 3 is a perspective view ofthe two sections 5o of the switch casing in disassembled relation; and Fig. 4 is an, enlarged elevational view, partly in section, to show one of the contact members on the outer side of the switch casing.

In the drawing, I indicates the outer casing 5B of the drill enclosing the electric motor which furnishes the power for rotating the chuck' shaft "or spindle 2. The motor, as shown, is of the horseshoe type having its armature 3 in the lower portion of the casing I and its field coil 4 in the upper portion of said casing. 5 The single handle 5 of the drill is of the pistol grip type. The handle is at the rear end of the casing I and extends outwardly therefrom in transverse relation to the axis of the armature 3. The handle 5 is hollow and comprises a forward 10 member 6 preferably cast integral with the casing I. The rear part 1 of the handle is removable providing a cover on the rear side of the handle for the compartment 8 which the handle forms `with the casing I l5 The hollow handle 5 provides/a duct for the intake ,of cooling air for the motor and is provided at its outer or lower end With-an opening 3. This opening allows for the intake of the cooling ain and also accommodates a cable I0 con- 20 taining the current supply Wires II, I2 for the tool. One part of the opening 9 is in the for- Ward part 6 of the handle and the remaining part is in the removable cover section 1, thus enabling the opening tobe split o n removing the 25 naled in ,ballbearings I4, Ila, one in the gear housing I5 at the front end of the drill, and the' other in the casing I at the handle 5. At this 30 location, the casing I supports a cup I6 in which the bearing Ma is mounted as shown inFig. 1. The cup |6 is preferably made integralwith the casing I and also receives a screw I'I for remov-- ably securing the rear part -1 of the handle 5 35 in place. n

'The gear housing I5 also contains the bearings I8, 18a for the chuck shaft 2 and the driving connection from the armature shaft I3 to the chuck shaft 2. This driving connection comprises a gear 40 I9 xed to the chuck shaft and in constant mesh with a pinion 20 provided on the armature shaft I3. vThe chuck shaft 2 is offset laterally from the armature shaft I3 and is disposed on the side of the armature shaft opposite the handle 5. 45

A rotary fan 2l is fixed to the armature shaft` I3 in the forward part of the casing I just rearward of gear housing I5. The fan member 2| is rotated by the motor and draws cooling air over the motor through the air duct provided by the hollow handle 5. I'he fan ZI discharges the air out of the casing I through a number of holes 22 in the casing at the periphery of the fan and in tangential relation thereto as in the Forss Patent No. 1,652,401, granted December 13, 1927. g5

Associated with the commutator 23 of the motor are two brushes 24, 25 each mounted in a brush holder respectively arranged above and below the axis of the motor as shown. The lower holder 26 is located in the handle part 6 and is electrically connected with the supply Wire II through a connector 21. The latter has a contact 28 to which the supply Wire is attached and said contact engages the metal conducting sleeve 29 in which the brush 25 is slidably mounted and normally urged against the commutatorby a spring (not shown) located in said sleeve. The connector construction constitutes the subject'matter of the Herman Kuehne application, Serial No. 45,545, filed October 18, i935.

The upper brush 24 is directly above the lower brush and is slidably mounted in a metal sleeve 30 in the holder case 3 I, which like the lower case 26 is made of suitable electrical insulating material. The upper brush holder 3l is removably mounted in the rear part of the casing I adjacent the cover plate 1 of the handle 5 in a channel shaped support 3Ia preferably made integral with the tool casing I as shown in Figs. l and 2. The metal sleeve 30 is exposed on its side facing the coil 4 of the motor. The upper brush 24 is also slidably mounted in its metal sleeve 30, and like the lower brush is normally urged against the commutator 23 by a spring 32, as shown in Fig. l. The outer or upper end of the sleeve 30 is closed by a plug 33 of insulating material screwed into the casing I to removably secure .the upper brush holder in said casing. A similar plug 34 closes the outer or lower end o1' the sleeve 29, and this plug removably secures the lower brush holder in the handle 5.

The switch device for the tool is located in the casing I in the space between the upper brush holder support 3Ia and the coil 4 of the motor as shown. The switch assembly comprises a casing comprised of two substantially similar, separable sections 35, 36, each made of an electrical insulating material, preferably light in weight and which can be die cast. The sections 35,36 are chambered as at 31 to provide a compartment for accommodating the active or movable parts of the switch mechanism when the sections are in assembled relation with their chambers in communication. The movable contact of the switch device comprises a substantially U-shaped element 36, the arms of which are respectively fulcrumed between two sets of lugs 36, 36, one set in each chamber 31 as shown in Fig. 3. The yoke portion oi' this switch member is connected by a 'coil spring 36a with an actuating button 46 slidably mounted at one end of the switch casing as shown in Fig. 2. This button has a shank piece (not shown) extending into the compartment formed by the chambers ,31 through a slot 4I provided along the `ioint between the sections 35, 36, the portions 4Ia, 4Ib of the slot being in the respective sections as shown in Fig. 3.`

.'I'heswitch deviceislocatedinthe casing I in transverse relation to the upper brush holder and has an interlocking connection with said holder for holding the switch device in the tool casing. This connection is formed by providing the switch case sections with outwardlybpening' side channels 42, 43, the former oi' which receives the upper brush holder casing 3l as shown in Fig'. 2. The toolcasing I hasalignedopenings 44, inits sidewallstoreceiveandsupporttheswitchcasing as shown. These openings conform to the shape of the switch casing'which is rectangular asshown. A Theswitchdeviceasaunitisslidendwise into the'casing through one opening. whereupon the upper brush holder is slid into place and interlocks with the switch device to hold it in place. The button 40 being at one end of the switch device is positioned at one side of the tool and within convenient reach of the thumb of the hand grasping the handle. The button is movable to the opposite ends of the slot 4I, and when at one end oi the slot opens the circuit to the motor, whereas when at the opposite e'nd of the slot closes the circuit. The lugs 46, 41 in the casing sections 35, 36 provide stops for the switch yoke 38.

In accordance with my invention, the casings 35, 36 are secured together in assembled relation by a single fastening member 48 which as shown in Fig. 2 passes through both sections in their overlapping portions exterior of the chambers 31. The fastening member is preferably in the form of a bolt having its head 43 and its clamping nut 56 countersunk in recesses provided in the respective sections. The latter have registering openings 5I, 5I for the bolt and these openings continue through dowels 52, 52, one on the inner side oi each section 35, 36. Each dowel projects outwardly to substantially the same extent from the inner surface of its associated section, and iits in a recess 53 in the opposite section when the sections are in assembled relation. The dowels and the recesses are non-circular in form and when interfltted prevent displacement of the casing sections 35, 36 about the axis of the bolt 46 or in the plane of the meeting edges of the sections. Thus, the latter are secured together by a single fastening' element Yinstead of by a number of elements as heretofore.- 'Ihis adds to the simplicity and the low cost of the switch construction and facilitates its assembly. The dowels 52 completely surround the bolt 46 when the parts are assembled, this being brought about by having a portion of each bolt hole in the associated dowel, as shown in Fig. 3.

The xed contacts 54, 55 for the switch device are carried by its respective casing sections 35. 36 in channels 42, 43 therein as shown in Fig. 2. These contacts are similar in form and each comprises a metal plate 56 which has integral tangs 51, 51- at one end iitting. in grooves 56. 56 in the side walls of the associated channel, as shown in Fig. 4. The tangs are co-planar with the plate and slide into the grooves on inserting the plate endwise into the channel. The plate, being of sheet metal, is resilient and carries a contact lug 56 at its end opposite the tangs. This lug snaps into an opening 66 in the associated casing section, and is exposedin the chamber 31 forengagement by the yoke piece 36 of the .switch mechanism when the yoke is `in on position.

Each plate 56 is provided with 'a struck out portion providing a spring tongue/6I. The tongue of the plate on the side ot the switch casing adjacent the coil 4 of the/motor contacts with a contact strip or bar 62 of the coil and in the electrical connection at one end with the coil winding 63 as at 64 in'Fig. 2; The tongue 6I of the other plate contacts the exposed side of the metal sleeve 36 of .the upper brush holder 3l, as shown in Figs. 1 and 2. Thus, the tongues 6I connect the switch device in the motor circuit and enable the switch de- \vice to control the supply of current to the tool.

.device is connected in the motor circuit on slidf ing the switch device into the casing. The wire I2 is connected to a stator wire l2a at a binding post l2b atl the connector 2l. The stator 55 extends through the bobbin 63a and down on" opposite sides of the armature 3, as in a horseshoe motor construction. The stator wire is connected to the coil winding 63. The motor circuit includes this winding, switch device, brushes, commutator, and the wires referred to. The switch casing is preferably divided long/,itudinally, that is, in the direction in which it is inserted into the casing I. The intake for the cooling air may be augmented by openings along the meeting edges of the handle sections 6, 1 as in the upper portions, a's at 68, in Fig. 1. The feature of the contact strip 62 in association with the switch device and the bobbin 53a and the construction of the bobbin constitute the subject matter of 'the co-pending Frithiof P. Forss application, Serial No. 45,541, led October 18,1935.

The gear housing I5 is provided with a cover plate `B6 on its rear side to divide lthe gear housing from the casing l. This plate constitutes apart of the gear housing assembly, which is removably secured tothe casing I by fastening screws 61; The cable lll is fastened to the handle section 6 by a clamping strip 68.

The channel 42 is deep enough to receive the brush holder case 3l so as to interlock the switch device with said holder.

The channel I3 is shallower sothat the tongue of the contact plate in said channel may extend out of the same to engage the bar 62 on sliding the switch device into the casing l. The channel 43 is made shallow by facingoif the'lbody of the casing section 36 after the same is made. Otherwise, the casing sections are 'alike, both'being duplicates 'when produced. This contributes to the simplicity of the construction, and as before stated, re-

duces manufacturing costs.

In this connection with making the sections 35, 36 duplicates, it is pointed out that the casing sections 35, 36 are' made with the dowels 52, 52 on the same side of the bolt holes 5i and with the recesses 53, 53 for the dowels on the opposite side of said holes. l'll'hus when the sections are assembled from the positions shown in Fig. 3, the dowel on one section will enter the recess on the other section.- Two openings are made in eachsection 35, 36, one adjacent one side edge of the section, and the other opening adjacent the opposite side of the section.

,This enables the contacts 59 for the switch piece 38 to be in opposition when the contact plates 5I, 55 are fitted in the channels I2, 43 from the same ends of said channels. Each channel has a set of grooves 53 at its opposite ends so that the contacts 59 may be reversed from the positions shown whenever desired. 'I'he extra set of grooves in the channel I3 are indicated in dotted lines 58a, 58a in Fig. 4.

The drill shown has a free speed of approximately 2500 R. P. M. and operates on the usual commercial electric current of 110 volts. The motor `is of the universal type, operating on either a D. C. or an A.'C. current. The drill is relatively small and' light in weight. It is held in one hand, and being small may be used in close quarters to drill at any desired angle.

The details of construction and arrangement of parts shown and described may be variously l changed and modied without departing from the spirit and scope of'my invention, except as pointed out in the annexed claims.

I claim as my invention:

' 1. In a hand drill of the character described, an

outer casing, an electric motor of the horseshoe type located in said casing and arranged with its armature in the lower portion of the casing and its field coil in the upper portion of the casing, a hollow handle at the rear end of the casing,

.upper and lower brush holders and brushes therein for the motor, the lower brush holder being located in the handle and the upper brush holder being located in the casing Vabove the handle and in spaced relation to the iield coil, a support in the casing for the upper brush holder, said coil having an electrical contact surface facing said support, and a manually operable switch device for the motor, said switch device being removably mounted in the casing between the upper brush holder support and the field coil and having yieldable contacts on its opposite sides to respectively engage the upper brush holder` and the field coil contact surface when the switch device is in operative position in the casing.

2;'In a hand drill of the' character described, an outer casing, an electric motor of the horseshoe type located in said casing and arranged with its armature in the lower portion of the casing, and its'eld coil in theupper portion of the casing, a hollow handle at the rear end of the casing, upper and lower brush holders and brushes therein for the motor, the lower brush holder being located in the handle and the upper brush holder being located in the casing above the handle and in spaced relation to the field coil, a support in the casing for the upper brush holder, said coil having an electrical contact surface facing said support, and a manually operable switch device for the motor, said switch device being removably mounted in the casing between the upper brush holder support andthe iield coil and having contacts on its opposite sides for electrical connection with the upper brush holder and the field coil contact surface, respectively, said switch device having a casing composed of a pair of substantially similar sections, each provided with one of the switch contacts.

3. 1n a .hand drin of tne'eharacter described,

A an outer casing, an electric motor of the horseshoe hollow handle at the rear end of thecasing, up-

per and lower brush holders and brushes therein for the motor, the lower brush holderbeing located in the handle and the upper brush holder being located in the casing above the handle and in spaced relation to the field coil, asupport in the casing for the upper brush holder, said coil having an electrical contact surface facing said support, and a manually operable switch device for the motor, said switch device being removably mounted in the casing between the upper brush holder support and the eld coil and having yieldable contacts for connecting the switch `deviceY with the upper brush holder and the eld coil contact surface, respectively, when the .switch device is in operative position in the casing. said switch device having channels in its opposite sides for the respective switch contacts, one channel being deep enough to have the upper brush holder intert therewith, and the other channel being shallower so that the switch contact in said channel may project beyond the same to engage the field coil contactA surface.

4. In a hand drill of the character desibed, an outer casing, an electric motor of the horseshoe type located in said casing and arranged with its armature in the lower portion of the casing and its eld coil in the upper portion of the casing, a hollow handle at the rear end of the casing, upper and lower brush holder and brushes thein for the motor, the lower brush holder being located in the handle and the upper brush holder being located in the casing above the handle and in spaced relation to the eld coil, a support in the casing for the' upper bmsh holder, said ileld coil having an electrical contact surface facing said support, and a manually operable switch device for the motor, said switch device being removably mounted in the casing between the upper brush holder supportl and the field coil and having yieldable contacts on its opposite sides to respectively engage the ,upper brush holder and the eld coil contact surface when the switch device is in operative position in the casing, said switch device having a casing composed of a pair of" separable overlapping sections, and a single fastening element for securing the sections in assembled relation. Y

5. In a hand tool of, the character described, an outer casing having side wallsan electric motor in said casing, spaced contact elements in the casing for the motor circuit, supports in the casing for said elements, said casing having aligned openings in its side walls between said supports. and a manually operable switch device insertable in the casing through said openings and having resilient contact members on its'opposite sides to engage said contact elements, said switch devicehavinganoutercadngconsistingofseparable sections, a switch operating mechanism located between said sections and having an operating button at one end of the sections, and means for securing the switch casing sections .5 together, said means being located adjacent the end of the sections opposite the button, said securing means comprising inte'riitting parts on the inner sides of the switch casing sections and a single fastening element extending through the i0 switch casing sections at the interntting parts and connned between the outer sides of the sections.

6. In a handtool of the'character described, an outer casing having side walls, an electric motor 16 in said casing, spaced contact elements in the casing for the motor circuit, supports in the casing for said elements, said casing having aligned openings in its side walls between said supports, and a manually operable switch device insertable 20 in the casing through said openings and having resilient contact members on its opposite sides to engage said contact elements, said switch. device having anvouter casing consisting of separable sections, a switch operating mechanism located 25 between said sections and having an operating button at one end of the sections, andmeans for securing the switch casing sections together. said means being located adjacent the end of the sections opposite the button, said securing means comprising interntting dowels and recesses on the respective sections, and a single fastening element extending through the switch casing sections at the dowels and recesses, respectively, and confined between the outer sides of the sections. $6

FRANK B. HAMERLYL 

